Method of making molded articles



June 7 1927.

W. N. BRIGGS METHOD OF MAKING MOLDED, ARTICLES Filed Jan 2. 1926 Fig.4.

Inventor" William N. BTL

HLs Attorney.

Patented June 7, 1927.

UNITED STATES PATENT OFFICE.

WILLIAM IN. BRIGGS, on rr'rmsrmnn, mnssncnusn'r'rs, ASSIGNOR TO GENERAL ELEC- TRIO comm, A CORPORATION on NEW YORK.

METHOD OF MAKING MOLDED ARTICLES.

Application filed January 2, 1926. Serial No. 78,780.

My invention relates to molded articles, and has for its object the provision of a simple, reliable and eiiicient method of making a molded article.

More specifically my invention relates to the making of molded articles from layers of sheet material impregnated with a suitable binder. As heretofore produced such articles have been built up from a plurality of layers of stampings from the sheet mate rial, these stampings being molded together and secured by the binding material by applying pressure against the sides of the sheets, i. e., the sheets are compacted together flatwise. The stamping of the sheet material in the required shapes is attended with a great deal of waste of material. This is particularly true in the formation of molded spoolsfor electrical windings in the construction of which the flanges have heretofore been'built up from a. plurality of stamped rings.

In carrying out gny invention I compact the article by compressing the sheet material edgewise whereby the article can be built up from rectangular or other suit- 7 ably shaped strips of material which can be out without waste. In the making of flange rings for spools, fore-Xample, a strip of the sheet material is wound into a coil which is then formed into a ring by compacting the convolutions of the coil edgewise'. This construction, furthermore, gives a much stronger article.

For a more complete understanding of my invention reference should be had to the accompanying drawing in which Figs. 1

' and 2 are views showing steps in the construction of a flange ring; Fig. 3 shows the application of a ring to the cylindrical portion of the spool prior to the molding operation; Fig. 4 shows a completed spool; while Figs. 5, 6 and 7 show a modification of .my invention. 7,

Referring to the drawing, I have shown my invention in one form as applied to the making of spools from sheet fibrous material impregnated with a suitable binder. This material may and preferably is wood pulp *impregnated with a phenolic condensation product. Obviously, however, any other suitable fibrous material impregnated with a binder may be used. The making of the spool can be, roughly, divided into two steps, the formation of a cylindrical porstitute flanges.

rial to ferm a flange ring of the required This strip 10 is first wound in spiral size. formation into a loose coil as shown in Fig. 1, the convolutions or layers of the coil being preferably spaced apart somewhat as indicated in the drawing. It will be observed that the successive convolutions of the coil are wound flatwise with respect to each other so that the transverse dimension of the strip at all points is parallel with the axis of the coil. The inside and outside diameters of this coil are roughly the same as the corresponding dimensions of the completed ring. The next step. is to place the coil in a suitable press by means of which pressure is applied to the sides of the coil. i. e. in a direction parallel with its axis whereby the convolutions of the strip are upset or compressed edgewise. In other. words, the coil is flattened into a disk-like ring 11, as shown in Fig. 2. The pressing device is preferably a mold which defines both the inside and outside diameters of the ring.

This compressing and molding operation may and preferably is carried out whilethe material is cold. The phenolic binding materialis not softened therefore so as to exert its maximum binding properties, but nevertheless the convolutions are compressed together and interlocked so as to adhere to a considerable extent, The cold When one or more intermediate flanges are to be formed on the spool, a ring 18 constrncted as described in connection with Figs. 1 and 2 is placed on the cylinder in the proper position and the assembled parts then placed in a mold. By means of the mold enormous pressures are applied and likewise suificient heat to soften the phenolic impregnating material. The mold also upsets each end of the cylinder to form flanges 1d and 15 (Fig. 4) on the ends in substantially the manner described in connection with Figs. 1 and 2. With these end 'fianges, however, heat is applied atthe same tlmt that the sheet material is compressed edgewise so that the flanges at the end are formed in one operation instead of being first compressed cold and then subsequently further compressed while hot as is the case with the-central flange. If desired, however, the end flanges may be formed from cold pressed rings slipped in the cylindrical portion, which in such case would have substantially the length of the completed spool.

This molding operation, as previously indicated, compresses the material into the desired shape and size, the binding material being then softened by the application of heat. The binding material is thus caused to not only bind the fibers of the respective sheets together, but also the sheets themselves. .4 The central flange ring 13 is thereby secured to the cylindrical portion and j shaped to form the central flange 16 of the completed coil. After the spool has been removed from the mold and the binding material allowed to harden the result is a solid homogenous spool having both great mechanical strength and dielectric strength.

As previously indicated, this principle in the formation of molded articles of compressing laterally 'lo'osely assembled layers or sheets of treated fibrous material has general application in the formation of molded articles, in addition to its application to, the making of spools. In Figs. 5, 6 and 7, I have shown its application to the making of molded bars. A plurality of strips 17 (Fig.

. 5) of a suitable size to make the finished article are placed in a mold and com ressed edgewise while cold into a square ar 18, as'shown in Fig. 6. As indicated in Fig. 5 the strips 17 do not fit tightly side'by side in the mold, sufiicient space being left to permit the strips to be upset. The bar 18 as mechanical strength to a marked degree,

he strips being interlocked together by the upsetting operation. place the cold pressed bar 18 into a heated The next step is to mold where pressure is again applied concurrently with sulficient heat to soften the binding material, preferabl densation product. The al step compresses the bar to the desired dimensions, after which the bar is taken out and allowed menace to cool. The completed her 19 is shown in Fig. 7.

- I have found that bars and other articles produced in this manner have much greater mechanical and dielectric strength than articlcs formed by pressing the sheet material together fiatwise. The strips when pressedtogether flatwise tend to separate upon the application of a considerable force. When the strips are upset, however, in accordance with my invention, they are interlocked so that a solid homogenous structure is formed.

It will be observed that the lengths of sheet material are placed loosely together to form a body Whose dimensions in a plane at right angles to the sheet material are approximately equal a) a cross sectional di-,

mension of the completed article. The di-i mension of the body formed by the loosely assembled lengths in the plane of the sheet material, however, is many times the corresponding dimension of the completed article. For example, the coil of Fig. 1 hasover-all dimensions in a plane at right angles to the sheet which are substantially.

the same as the corresponding dimensions of the'flange ring 11 of Fig. 2. The dimension of the coil at right angles to this plane, however, i. e., the height, is many times the height of the flange ring. Similarly, in Fig. i 5, the loosely assembled strips 17 form a plane at 1y equal 1 body which has dimensionsin a right angles to the strips substantia to the similar dimension of the completed article. During this first cold pressing op eration the only diinension'changed to any extent is the one at right ang es this plane. The articles 11 and 18 of Figs. 2 and 6 resulting from the: cold pressing operation have substantially the dimensions of the completed article and the finishing molding operation compresses these articles somewhat uniformly.

While I have described my invention as embodiedin concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The method of forming a molded article which consists in loosely assembling a plurality of layers of sheet material, compressing'said layers edgewise while cold into a solid mass having approximately the dimensions desired, and then further compressing said mass uniformly in. all direc tions in a heated mold.

2. The method of forming a molded article which consists in providing strips of fibrous material impregnated with a phenolic condensz'dzion product, placing said strips in a mold and compressing them edgewise while cold into a solid integral body, removing said body from said cold mo d, placing said body in a heated mold, and further compressing said body while heated to a temperature sui'licient to soften said impregnating material.

3. The method of forming the flange ring a spool which consists in providing a strip of fibrous material impregnated with a phenolic comlensation product, winding said strip into a spiral coil, and then compressing said coil edgewise While cold so that the turns are crushed into interlocking relation and secured by said impregnating material to form a solid integral body.

4. The method of forming a spool which consists in Winding a strip of treated fibrous material into a loose coil, applying pressure to flatten said coil into a ring, placing the ring thus formed on a cylindrical portion, and then compacting and forming the cylinder and ring in a heated mold.

5. The method of forming a molded spool which consists in winding a strip of treated fibrous material into a loose coil applying pressure to flatten said coil into a ring While cold winding a cylinder from a sheet of said fibrous'inaterial. placing the previously formed ring on said cylindrical portion in position to form a central flange, and then compacting and forming the cylinder and ring in a heated mold so as to upset the ends of said cylinder to form end flanges.

6. Themethod of forming a molded spool from fibrous sheet material. impregnated with a phenolic condensation product which consists in forming a flange for the spool separately by winding a strip of said material into a loose coil and. flattening said coil While cold in the direction of its airis into a solid ring, rolling a sheet of said mate rial. into a cylinder, placing said ring on said cylinder and then compacting and shaping the cylinder and ring into a solid integral body in a heated mold.

in Witness whereof IV have hereunto set my hand this 28 day of December, 1925.

WILLIAM N. BRIGGS. 

